The use of porous films is prevalent in many advanced electrochemical systems for energy conversion. For example, in both polymer exchange membrane fuel cells (PEMFCs) and solid-oxide fuel cells (SOFCs), porous films can be used to reform hydrocarbon fuels to liberate hydrogen gas and/or to serve as the conductive electrodes to transport current. Since miniaturized fuel cells are of interest for applications in portable power generation, the processing of film components at both low and high temperature becomes evermore significant for enhanced performance. In addition, methods for film processing integral components should be compatible with the device thermal history to ease manufacturing.
Porous and conductive films are used as integral components in many types of electric power generating devices and sensors. A wide range of commercial products exist in consumer electronics, e.g., cell phones and laptop computers. Methods to produce conductive and porous films are in general limited by the size of the pore obtained. In addition, complex synthesis methods involving gaseous and/or aqueous processes often generate toxic byproducts and wastes. For example, an advance in the pursuit of fabricating porous conductive films near room temperature relies on photolithographic patterning and etching process steps.
The following articles, which are hereby incorporated by reference, describe general observations regarding the stabilization of basic coating morphologies found in the classic zone models. Also described are experiments of film growth. B. A. Movchan and A. V. Demchishin, Phys. Met. Metallorg., 28 (1969) 83; J. A. Thornton, J. Vac. Sci. Technol., 11 (1974) 666; J. A. Thornton, J. Vac Sci. Technol., 12 (1975) 830; J. A. Thornton, Ann. Rev. Mater. Sci., 7 (1977) 239; J. A. Thornton, J. Vac. Sci. Technol. A, 4 (1986) 3059; J. A. Thornton, SPIE Proc., 821 (1987) 95; and R. F. Bunshah and R. S. Juntz, Metall. Trans., 4 (1973) 21.
Other articles related to the art include the following and are also hereby incorporated by reference: A. F. Jankowski and J. P. Hayes, J. Vac. Sci. Technol. A, 13 (1995) 658; M. Neirynck, W. Samaey, and L. Van Poucke, J. Vac. Sci. Technol., 11 (1974) 647; D. Queheillalt, D. Haas, D. Sypec, and H. Wadley, J. Mater. Res., 16 (2001) 1028; J. Morse, R. Graff, J. Hayes, and A. Jankowski, Mater. Res. Soc. Symp. Proc., 575 (2000) 321; A. F. Jankowski and J. D. Morse, Mater. Res. Soc. Symp. Proc., 496 (1998) 155; R. Messier, A. Giri, and R. Roy, J. Vac. Sci. Technol. A, 2 (1984) 500.